Hollow fiber liquid phase microextraction combined with electrothermal vaporization ICP-MS for the speciation of inorganic selenium in natural waters

Abstract

A novel method for the speciation of Se(IV) and Se(VI) in environmental water samples based on liquid-phase microextraction (LPME) methods in conjunction with electrothermal vaporization (ETV) ICP-MS has been developed. Two modes of LPME: single drop microextraction (SDME) and hollow fiber liquid phase microextraction (HF-LPME) were studied comparatively. The organic chelating reagent ammonium pyrrolidine dithiocarbamate (APDC) was used as both the extractant for microextraction and the chemical modifier for ETV-ICP-MS determination. Under the optimal conditions, enrichment factors of 75 and 410 could be achieved for SDME and HF-LPME, respectively. The detection limit of Se in HF-LPME-ETV-ICP-MS and SDME-ETV-ICP-MS were 0.50, 0.56 pg mL⁻¹ and 2.7, 3.0 pg mL⁻¹ for Se(IV) and Se(VI), respectively. HF-LPME was finally selected for the analysis of Se(IV) and Se(VI) in lake water, river water and pool water samples due to its good analytical features and robustness. The proposed method was validated by the determination of total Se with PN-ICP-MS.